Filter



May 13, 1952 R. P. DUNMIRE FILTER Filed July 16, 1947 Patented May 13,1952 UNITED STATES PATENT OFFICE FILTER Russell Paul Dunmire, Orange,Ohio Application July 16, 1947, Serial N 0. 761,220

4 Claims. 1

This invention relates to an apparatus for and process of treatingliquid and semi-liquid materials, which contain light volatiles, gasesand solids, adapted to filter the material to remove therefrom solidparticles, including micro and macro particles, and to substantiallysimultaneously separate and remove the gases and low boiling pointconstituents from the filtrate or liquid portion of the material. In oneapplication of the invention crank case oil may be treated to extractfrom the oil solids and other foreign matter and to remove low boilingpoint contaminants in a gaseous phase therefrom. In another application,the apparatus embodying the invention may be interposed in thelubricating oil feed line of an airplane, so that when the latter ismaneuvering at high altitudes, and foaming and frothing develops in theoil, due to low atmospheric pressure and the presence of low boilingpoint and gaseous contaminants and also other impurities such as solidcontaminants, including metallic particles, carbonaceous substances andsludges, the oil may be purified of these contaminants and impurities toavoid unsatisfactory engine lubrication. A further application of theapparatus embodying the invention consists in interposing the apparatusin fuel supply lines, especially airplanes, for continuously removingfrom the fuel, moisture and solid contaminants to eliminate the use offilter cartridges, which are not self cleaning and clog in a relativelyshort time, and therefore have to be repeatedly replaced. Other types ofliquids or liquid materials may be treated; for example, in variouschemical treatments where it becomes necessary to remove. from thematerial being treated low boiling point portions and/or solids or it isdesirable to recover these substances.

One object of the invention is to provide an improved apparatus of thistype wherein liquid containing 'low boiling point constituents andgases, as well as solids, including micro and macro particles, may befiltered and such substances substantially simultaneously removed.

Another object of the invention is to provide an improved apparatus ofthis type of relatively simple construction and capable of continuouslyfiltering liquid material and removing therefrom low boiling pointconstituents, gases, solids and semi-solids.

Another object of the invention is to provide an improved apparatus ofthis character wherein the'supplied material to be filtered is heatedand a connection with a vacuum pump or other source of vacuum isinterposed between the 2 filtering wall and the discharge outlet for thefiltrate, whereby the gaseous constituents of the latter are removedtherefrom.

Another object of the invention is to provide an improved process offiltering liquid adapted to simultaneously remove low boiling pointportions thereof and gases therein, together with solid and sludge-likecontaminants in a continuous manner.

Another object of the invention is to provide an improved filteringprocess for continuously removing from liquid solids and semi-solids bymeans of centrifugal agglomeration, countercentrifugal filtration and.flash evaporation of the low boiling point contaminants.

Another object of the invention is to construct an improved filteringapparatus embodying certain improvements in the apparatus shown in myco-pending application Ser. No. 535,062, filed May 11, 1944, now LettersPatent No. 2,442,234, dated May 25, 1948.

Other objects of the invention will be apparent to those skilled in theart to which my invention relates from the following description takenin connection with the accompanying drawing, wherein Fig. 1 is a view,partly in section and partly in elevation, of an apparatus embodying myinvention, and capable of carrying out the herein disclosed process.Fig. 1a is a fragmentary section of parts shown in Fig. l, enlarged.

Figs. 2 and 3 are sections on the lines 2--2, and 3-3 respectively, ofFig. 1.

Fig. 4 is a fragmentary section on the line 4-4 of Fig. 1.

In the drawings, I indicates as an entirety an outer casing to which thematerial to be filtered is delivered. 2 indicates as an entiretyfiltering or separating means within the casing I and driven by asuitable motor 3, preferably mounted on the casing l by means of abracket 3a, in connected relation to the filtering or separating meansto illustrate one form of driving means for the latter.

The filtering or separating means includes a casing 2' having an annularwall 2a: which is formed of porous or foraminous material and throughwhich the filtrate flows to effect filtration or separation of thesupplied material, this wall being rotated about its axis by the motor 3(as hereinafter set forth) to establish outwardly thereof a centrifugalforce eifective to act on those portions of the material (solids andparticles) that are to be separated therefrom.

By preference, the filtering wall forms the side wall of the casing 2',which is bodily rotated by the motor 3.

As set forth in my aforesaid co-pending application, the apparatus isadapted to operate on a wide range of materials. Accordingly, the sizeof the openings in the filtering wall will depend upon the kind orcharacter of material to be filtered, its pressure and the speed ofrotation of the filtering wall; also, where the material to be filteredconsists of a liquid; the speed of rotation of the filtering wall andthe size of the openings therein will depend upon both the viscosity andpressure of the liquid.

The outer casing I consists of upper and lower heads la, lb, formed withannular seats for an annular wall lo and secured togethei 'and to thewall lc by bolts Id. The opposite-ends of the wall lc engage suitablegaskets le pro vided in the seats, whereby the casing l is m'ade liquidtight. Either head or both heads la, lb, may 'be provided with suitableinstrumentalities (not shown) whereby the apparatus; may" be mounted ona suitable support-'01; framei of a machine; depending-on the specificapplication of the apparatus. In'theform of construction disclosed-thewall la is formed of transparent material; such as'glass. The head,la'isnformed' with an .inlet If; the wallsof which are pref. erablyprovided with screw threadsto "receive and mount a nipple 4,removablyconnected-"by a coupling 4a to a supply pipe-5,'throu'gh whichthe material to be filteredoroperated yupon-is supplied under pressure:In the'preferred form of construction, thepipe 5 isconnected to" theoutlet end of asuitable rotaryipump Gsupported on brackets to which'aresecured to theicasing ofthe'motor's, the rotor of "the pump 6 beingdrivingly connected to the" shaft of the motor 3;, whereby one motor isutilized to I drive both the-inner casing 2' and pumpli; The: materialto be operated upon is supplied underpressure by gravity or otherwisebyfa'pipe 1- suitablyconnected'to the inlet end or side of the pump Thepump Q-beingdisposed in' close relation to the outer casing'l, itinsures 'deliverypf'the material through the inlet If into the casing Iat adequate pressure to insure flow-of thefilt'ered material into thecasing "2", *whereas' the casing 2ais rotated, the effect of whichis,-to=establish outwardly thereof a centrifugalforce whiclrl-acts ontheheavy and/orsolid portions of" the-supplied material in opposition: toithe pressure thereof to prevent accumulation of such portions on thefiltering wall-of the-.casing- 2"'=:and-efi'ect outward movement thereofas later set forth.

Accordingly, it is advantageous to "provide-a pump. in close relationto:the.inlet for the casing lftOll'lSlllE a uniformsupply of the*material at theproper pressure thereto. -.-The:- head "to is providedwith an annular upwardly extending collar-8, which is concentric to-theaxis of 'the casing l and -removably' supports a-:-cap-'9 to form archamber It, for a purpose laterset forth, the side wall of the collarbeing formed with a screw threaded outlet opening towhich a dischargepipe" H (later'referred to) is -connected; :The lower head lbie-provided with'a downwardly extending collar 8a, which isconcentrictothe axis of the casing l and provided witha removable cap 9a to form achamber Illa,- fora purpose later -set-forth-, the sidewall of thecollar being formedv with a screwthreaded outlet ;.opening to which isconnected atdis:

charge pipe .l la leading to a suitable reservoir (not shown). Thelowerhead lb is formed-with one or. more openings .lg'. (six openingsglg-iri annular arrangement around the collar 8a being shown) throughwhich that portion of the material, which is prevented from filteringthrough and into the inner casing 2, gravitates or is directed, as laterset forth, into an annular col lector l2.

By preference, the side walls of the collector [2 are provided withflanges 12a, the outer flange being formed'with screw threaded openings,to re'ceivel'th threaded ends of the bolts ld, whereby"'the" latterare"utilized to secure the collector l2 in position and the heads la, lb,and wall lc together. As shown, gaskets l2.b are provided between theflanges Ho and head lb to prevent leakage from the casing l. The bottomwall of thecollector I2 is provided with one or more valved drainopenings l2x (preferably six openings l2asee Fig. 2) through which theseparated out solids and/or particles may be discharged into asupplemental collector l2c, so that whemithe-i'collector5-12isfull itmay be emptied of eit's i'contents:without stoppingthe operation or:the*apparatus';' The supplemental collector l Zc iSf'Of annular-shapeand'its top'wall is formed with openings lZdAone for eachopening l2m)and i adaptedito register therewith, respectively, inzenezpositiorrof=thesupplemental collector I20. As showr'f isee Figs-fl and 1a)the'side walls of theicollector: I2c, at-their upper ends are providedwith flang'es' l2d', which are movably supported on and overlap annularplates 'lZe suitably fixed tozitlreebottomxwall"of the collector l2,whereby the collectorrl2c"may be rotated to one position to-riclose thevalveopening's l2zc (see Fig. 2) and to'anotherposition'into'registrywith the valve openingsfiliwlsee' Figs; 1 and 1a) when the collector -[2is to 'be emptied. The supplemental collector 12c is provided with aremovable bottom'wall IZ'f} whichis held in'position by thumb screws:l*2g-to permit removal of the wall I2 andidi'scharge of. the solidsand/or particles from the:- supplemental collector" 12c. Thesupplemental-fcoll'ector IE0 is rotated by suitable handles l27tto-.=po'sition"the"openings l2d'into or out of registry with" theopenings I 2x.

a' Ilier-casin'g. 2! "comprises the following: 2a indicate's a.-'ho'llow shaft closed at its lower end. Tl'ie uppr endpo'rtion of theshaft 2a extends through aline'd': openings'formed in the upper heade'lw and' cap and supported in anti-friction bearifigs l 3;".the upperend of the shaft being connectedby a coupling 9b to the adjacent endoftlie isliaft 312i of'themotor 3. A gasket is interposedbetween thep'arts'of the coupling Slb t'o s'e'al'fthe upper' endpf the shaft 2a. Inthe arrangement-illustratedtheiipper end of the cap 'srecessedfas shown'at Qd to accommodate the ami-rrieudnbearings 13 between it and theshaft 2a, the bearings l3 beings'ecured in positi6n by ""an annular ringl4,'removably bolted to th'e -cap "Ihe lower'end' portion of the shaftxtends through alined openings formed in the bottorrfliead jlb and cap9a and supported in' anti friction"bearings l3a, preferably mounted inthe cap*9d"sir nilarly to the bearings l3. Ii /l6, indicate'space'dfupper and lower heads e'abhhavingfa"hollow boss ll fitting theshaft zaiasai-embivamy secured'thereto by a set screw inner 'fac'e'spfthe heads l5, l6, adjacent their peripheries, are formed with alinedrecesses l9 which form seats for the opposite ends ofthe' poi'ou's orforaminous wall 2r. It will be il llhtfihl l i e of n ed thickness and:thefopenings therethrough may begof varyingsizesforreasons already setforth.

Where a porous wall is employed, it may be formed of carborundum,carbon, compressed powdered metal, disks, or artificial stone. The seatsl9 are preferably annular and the wall 2a: is preferably formed of asingle section of material shaped in cross section to removably fit theseats l9, whereby the casing 2 is of true cylindrical form, but theinvention is not to be limited to a wall of this cross-sectional shape,since the centrifugal force set up due to the rotation of the casing 2'will be effective where this wall is sectional or of some other shape,Suitable gaskets are interposed between the opposite ends of the wall2a: and the bottoms of the seats I9 to prevent leakage of the filtratefrom the casing 2'. The shaft 2a, below the head I5, is formed with aplurality of openings 21), the purpose of which will later be set forth.2| indicates an impelling member in the lower end of the casing 2' andfixedly related to the shaft 2a and head IS. The member 2| consists of adisk 2 la having a hub suitably secured to the shaft 2a and provided onits outer circumferential side wall with inclined blades 21?), the freeedges of which engage with and are seated against the inner side wall ofthe head I6. As the impelling member rotates with the shaft 2a andeasing 2', the blades 2lb serve to impel a downward fiow of the liquidportion of the filtrate in the casing 2'. As shown, the head I 6 isconically shaped and cooperates with a plug 2 I as within the shaft 2ato form a chamber lESa below the impelling member 2| and the shaft 2a isformed with openings 2| 0 to permit fiow of the liquid filtrate into thehollow shaft 2a. That portion of the shaft 2a which extends through thechamber Illa is formed with elongated openings 22 to permit fiow of theliquid filtrate into the chamber Illa and discharge therefrom throughthe pipe Ha. That portion of the hollow shaft 20, extending through thechamber In is formed with a plurality of elongated outlet openings 2c toprovide for the flow of air and/or gases from the casing 2' into thechamber I9.

23 indicates as an entirety an evacuating means consisting of a suitableexhaust pump 23a having an intake to which the discharge pipe II isconnected and a discharge pipe 23b connected to a suitable liquid andair or gas separator 230. The pump 23a is driven at a constant speed bya suitable motor (not shown). The evacuating means 23 operates (a)primarily to volatilize the low boiling point constituents contained inthe filtrate filtered through the wall 2x into the casing 2' and removeair and/or gases from the casing for discharge through the exhaust pipe23d and (b) secondarily to provide a reduced pressure in the casing 2'toaccelerate the flow of the filtrate through the wall 22:.

Means, indicated as an entirety at Ix, are provided for supplying thenecessary amount of heat to the liquid being treated prior to fiowing orfiltering into the casing 2' or while passing through the latter toprovide the latent heat of evaporation to fractionate off the lowboiling point constituents of the filtrate, although under somecircumstances the heat generated by the friction between the rotatingfiltering wall 25c and the material being treated will be sufiicient forthis purpose. The heating means Ir herein shown consists of a suitableresistance coil, coiled around the wall lc (preferably exteriorlythereof) and connected with a source of electric current supply, whichmay be regulated in a well known manner.

24 indicates a pair of plates surrounding and closely fitting the shaft2a within the chamber Hi and engaged by a coiled expansion spring 24::which normally holds the plates in engagement with the bottom wall ofthe chamber I0 and inner face of the cap 9. 2% indicates a suitable sealmounted in an annular recess formed in the lower side or face of thehead la and having a spring operated sealing element engaging the shaft2a to prevent the escape of material in the casing l, due to pressure orcapillary attraction, into thecha nber i0. 240 indicates a suitable sealmounted in an annular recess formed in the cap 9 below the bearing l3and having a spring operated sealing element engaging the shaft 2a toprevent the escape of material in the chamber 10 into the bearing andoutwardly therethrough. 25 indicates a pair of plates surrounding theclosely fitting the shaft 2a, within the chamber Illa and engaged by acoiled expansion spring 25a which normally holds the plates inengagement with the top Wall of the chamber um and inner face of the cap9a. 26 indicates a suitable seal mounted in an annular recess formed inthe upper face of the head lb and havinga spring operated sealingelement engaging the shaft 2a to prevent the escape of material in thecasing 1. due to pressure or capillary attraction into the chamber Illa.26a indicates a suitable seal mounted in an annular recess formed in thecap lid above the bearing 13a and having a spring operated elementengaging the shaft 2a to prevent the escape of material in the chamberW60 into the bearing and outwardly therethrough.

To divert the material in the casing l away from the seals 24b and 26, Iprovide on the shaft 2a adjacent each of these parts a plurality or setof outwardly extending arms or wings 2x, therevolution of which by theshaft imparts movement to the material outwardly. In the form ofconstruction shown the arms or wings 29a of each set consist of ridgesembossed on a metal disk which is provided with a collar secured to theshaft 2a in any desired manner.

21 indicates a plurality of collecting members, each being preferablyU-shape in cross: section, uniformly spaced around the inner face of thewall is, the outer side portion of each member being secured to the walllo in any desired manner, so as to dispose their open ends in opposedrelation to the direction of rotation of the casing 2. By preference,the members 27 extend from end to end of the casing I at an angle to itsaxis and their lower ends are connected to the openings I g,respectively. The members 21 serve to collect the separated out solidsand particles, and to set up therein a centrifugal force counter to thatestablished by the rotating wall 2a", so that these solids and particlesor portions thereof agglomerate into larger bodies or masses and toguide them downwardly and also serve to prevent rotative movement of thematerial (or portions thereof) supplied to the casing I due tofrictional contact of the rotating casing 2' therewith, as Well as setup a turbulence in the material, the effect of which is to acceleratethe separation of the solids and particles from the liquid portion ofthe material. By preventing rotation of the material in the casing I,the outer surface of the wall 236 of the casing 2' is continuouslywashed by portions of the material without unduly affecting the'ilow ofthe liquid material through the wall 2a: due to the pressure of thematerial sup. plied tothe casing I.

Operation.-In" practicing my invention, the material to be treated isforced under pressure amass by the pump 6 through the pipe 5 into thecasing I, the liquid portion or the material being forced through therotating wall 2:: into the chamber or casing 2". As the "wall 211: isrotated, a centrifugalforceis established outwardly thereof, the effectof which is'to repel the solids, particles andsludge-like contaminantsoutwardly into the collecting members 21, which set up a countermarimgnforce and cause the solids, particles and constituents to agglomerateinto bodies or masses and direct the latter downwardly, due to is rat ofth s b through the openings lb int the collector l2, from which hermarbe r mqved- T q i and low boiln si -me i s. there n re heated y he fritionq b 'ts rlisd ma e a wit t tatin wa 1 of $1 ,7 1 by heh ti means nqe'ss r q d s a e, to su thek tgi 35 2 Q 5 fiY p t 0. the filtrate a d'n ss'mrm sh he c i a e h a'n mlwm e .3 S d vi e. the i id o' n str m ore ic es! Q. etwhen sp s o o acted 1 0.12 b e. high Y smin! n th c i 27'e o boiling point contaminants, are immediately volatilized and drawnoil by means of the vacu-. um p mp, 2.3a, whereas the evacuatedparticles of. liquid gravitatato and collect in the bottom of-tlie.casing 2 whereby they are acted upon by the, i'mpelling, element 2 l andforcibly discharged through the chamber 1 8a, and shaft 2a into the,chamber, Lila. for discharge through the pipe I la. 'ihelintalge of airand return flow of the liquid through thepipd Ha may be prevented bymeans ofa 'suitableflow pressure relief valve (not shown) set-Lat apressure substantially higher than the pressure. within the. rotatingfilter casing 21!, Y 7

"Ijhus itwill be noted, that the steps of separating the solids andparticles from the liquid portion or the material, the agglomerating ofthesolids and particles into masses and discharging them front thecasing l, filtering of the liquid; pqaaaorthe material, evacuating thegases 'andlowboiling point constituents in the filtrate anddischargingthe evacuated liquid are carried; on continuously; and, simultaneously.As there is acont'nuous supply, of. the material tothecasing] ana:continuous-centrifugal force imparted; tame, he iavyforv solidportions thereof; the, latter l are foroed outwardlyand then downwardlyinto the, collector l2; due to the" angular arrangement ofthe,deflectors- 21. Accordingly, it will; beobserved that thefilteringwall 2:1: is automatically, maintained free of; those portions ofthe;material; which would clog or tend to clog the pore s thereof;sothat the supplied material is rapidly. and; efiiciently, filtered;also that therateof flow orpressure of the supplied ma terialmust be,regulated or the speed ofthe casing\ 2i be regulated;v so that thecentrifugal force establishedwill notprevent the in-fiow of materialinto thacasing 2, but will operateeffectively .upon the heavierv and/orsolid portions of. the material without unduly affecting the flowofrthei filtrate into casing. 2. In other words, the speed; of :the-.casing. 2 must be related to or balancedagainst therpressure of thesuppliedmateriali Where thematerial-to be filtered is'a; liquid, this.speed and pressurev must be regulated with respect to the, viscosity ofthe material, to-insure=fiow of the liquid or fluid at afpredeterrninedrataandgrapidrand efficient op-., eration,"

The speed of the motor 3 vmay-abesregulatcd-by a siiitable ,rho'stat231; also l'rldesired, a: suitable speed change mechanism may beinterposed between the motor 3 and pump 6 to meet'varying conditions,dependent upon the kind and/ or viscosity of the material, to beoperated upon.

It will be observed that the type, character or construction of the wall2.1: will depend upon the kind of material to be filtered and/ or thecharacter or size of the heavy particles or bodies therein. For example,this wall may consist of sheet metal formed with openings of any desiredsize, Wire mesh oi any desired screen capacity per square inch.

29 indicates a suitable condenser interposed in the pipe H- between thegas receiving chamher It and; the evacuatin means 23, wherein the lowboiling point vapors are condensed to liquid anddischarged through anoutlet 29a for collec tion in any desired; manner, whereas thenoncondensabl-e vapors flowto the pump 23a and are discharged into theatmosphere through the pipe 2351 Water or other coolant is supplied bypipe 2st; to the container 29; and discharged therefromthrough the pipe2 90.

No claim is made herein to the subject-matter disclosed in my aforesaidc-o-pendingapplication and/or my co-pending application Serial No.'738,333,fi1ed; Mar, 31,1947, nowabandoned.

Tothoseskilled in the artto which my invention relates, many-changes inconstruction and widely difiering embodimentsand applications: oi theinvention will suggest themselves without departing from the spiritandscope of the invention. My disclosures and the description herei arepurely illustrative and arenot intended to be in any sense limiting.

What v I' claim is;

i. In afiltering apparatus, the combination or a substantially liqui dtight. stationary casing, on s in Qii upper. andlqw end Walls and a,side wall and having a material supply inlet in its upper portion and; adischarge outlet in its qwe fn r oa, m ans o upp i h material to be fltered under pressure to said inlet, a separate liquid; tight casingrotatably mounted within'said stationary casing and consisting of upperand lower heads and a porous side wall through which the liquid portionof the material flows from saidstationary easing into said rotatahleoasin a hollow shaft extending axially hrough a dm atah e a n ndt e pp ra d lower endwails of saidstationary casing, means on theouter sidesoi-saidend walls ,for r-otatably supporting s,a id s hait, said shaftbeing connected to the heads oi said; rotatable'casing to rotate thelatterwhen the shaft is driven and closed at its opposite ends a wall insaid shaft adjacent thelowerhead'oi saidrotatable casing for closing theopening through said, shaft to provide a conduit for air and gasesvextending upwardly through said upper endwall and a conduit for theliquid'portion'ofthe filtrate extending down- Wardly through said; lowerend Wall, the side Walls Of said shaft, being formed within saidrotatable casing and above and below said closure wall; withinletIopening-sand between each end walhof saidstationary casing and theadjacent supporting means-for said shaft'with outlet openings adischarge'lpipe; an evacuating means for air and gasesconta-ined in thematerial, connections r61 the-floWof'air-and gas leading fromsaidoutletopeningsat -theupper end portion of said sh-ait--to saidevacuating means, connections forthe fiow ofthe liquid portion'of thefiltrate leadingdrom'qsaid -outlet openings atthe lower end portion ofsa'id shaft and connected to said discharge pipe, and means for rotatingsaid shaft, whereby the side wall of said rotatable casing, due torotation thereof, sets up a centrifugal force effective to acceleratethe separation of the solids and particles in the supplied material fromthe liquid portion thereof.

2. An apparatus as claimed in claim 1 wherein said shaft in the plane ofsaid closure wall is provided with an impeller arranged to induceflow-of the liquid portion of the filtrate from said separate rotatablecasing into said liquid conduit.

3. An apparatus as claimed in claim 1 wherein the lower end wall forsaid stationary casing within and adjacent its side wall is formed witha plurality of discharge outlets, an annular collector for the materialdischarged through said discharge outlets is secured to said lower endwall and an supplemental collector is rotatably mounted on the bottomwall of said collector, the walls between said annular collector andsaid supplemental collector being formed with openings each of which inone wall registers with one of the openings in the other wall in onerotative position of said supplemental collector to permit discharge ofthe material in the annular collector into said supplemental collectorand to prevent discharge of the material into the latter in anotherrotative position of said supplemental collector, said supplementalcollector being provided with a removable wall to permit removal of thematerial discharged thereinto.

4. In a filtering apparatus, the combination of a substantially liquidtight stationary casing, consisting of upper and lower end walls and aside wall and having a material supply inlet in its upper portion and adischarge outlet in its lower portion, a closed chamber incorporatedwith and disposed on the outer side of each of said end walls, means forsupplying the material to be filtered under pressure to said inlet, aseparate liquid tight casing rotatably mounted within said stationarycasing and consisting of upper and lower heads and a porous side wallthrough which the liquid portion of the material flows from saidstationary easing into said rotatable casing, a shaft extending throughsaid rotatable casing axially thereof and the upper and lower end wallsof said stationary casing and into said chambers and fixed to the upperand lower heads of said rotatable casing and rotatably mounted at itsopposite ends in the outer end walls of said chambers, the upper endportion of said shaft beinghollow and formed within said rotatablecasing with a port through which air and gases in the filtrate in saidrotatable casing flow into said shaft and within the adjacent chamberwith a port through which air and gases flow into the latter, anevacuating means, connections between the chamber into which the air andgases flow and said evacuating means, a discharge pipe, the lower endportion of said shaft being hollow and formed within said rotatablecasing with a port through which the liquid portion of the filtrateflows into the adjacent hollow portion of said shaft and within theadjacent chamber with a port through which the liquid portion of thefiltrate flows into the latter, connections between the chamber intowhich the liquid portion of the filtrate fiows and said discharge pipe,and means for rotating said shaft.

RUSSELL PAUL DUNMIRE.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 702,795 Holmes June 17, 19021,026,075 Coombs May 14, 1912 1,799,590 Kiefer Apr. 7, 1931 2,095,470Foley Oct. 12, 1937 2,103,635 Palmer Dec. 28, 1937 2,442,234 Dunmire May25, 1948 FOREIGN PATENTS Number Country Date 245,860 Great Britain Jan.18, 1926

